you need to contact your service provider. some will bar 'roaming', as it's termed, initially but release the bar providing your credit record is good. you can ask them about costs at the same time but my major piece of advice is that you get charged for incoming calls whilst abroad as well as outgoing calls. you can quickly run up very large bills. texting is usually the same price (or very similar) to what you normally pay so this can be an economical way to communicate whilst abroad.